Image processing apparatus, image forming apparatus, image processing method, and computer program product

ABSTRACT

An image processing apparatus includes a scanner that receives image data, an area extracting unit that extracts image data of visually different image areas from the received image data, an HDD that stores therein the extracted image data, a criterion storage unit that stores a plurality of criteria for identifying each of the image areas as one of processing areas, a device interface unit that receives a selection of an image segmentation mode from a user, a selecting unit that selects a criterion from the criteria stored in the criterion storage unit based on the selected image segmentation mode, and a processing unit that identifies each of the image areas as one of the processing areas based on the selected image segmentation mode and performs image processing corresponding to the identified processing area.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to and incorporates by referencethe entire contents of Japanese priority document 2008-170058 filed inJapan on Jun. 30, 2008 and Japanese priority document 2009-097122 filedin Japan on Apr. 13, 2009.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a technology for controlling processingcontents of image processing in an image processing apparatus.

2. Description of the Related Art

When image processing is to be performed on optically-read image data,processing contents of the image processing are typically changeddepending on a type of the image data.

For example, when the image of the image data mainly contains text,binarization and the like is performed on the image data to sharpenedges of the text, and, when an image of the image data mainly containsphotograph and the like, image processing that can maintain color toneof the image is performed on the image data. To change the processingcontents in this manner, it is necessary to properly identify contentsof the image of the image data.

Japanese Patent Application Laid-open No. H3-64257 discloses atechnology for setting a criterion for identifying contents of imagedata (hereinafter, “image type”) as either a line image or a halftoneimage so that a user can identify the image type according to users'preference.

In the conventional technology disclosed in Japanese Patent ApplicationLaid-open No. H3-64257, when image data stored in a storage unit is tobe reprinted, the image data can be reprinted only based on the imagetype identified under a previously-set criterion is stored in thestorage unit. However, there is a demand for changing the image typebefore reprinting the image data depending on a use purpose of the imagedata.

However, in the conventional technology, if an image of image data hasbeen printed out once, the image data is stored in the storage unit in aformat obtained after the image data has been subjected to imageprocessing such as the binarization process according to the image typeidentified based on the previously-set criterion. Therefore, the imagetype of the image data stored in the storage unit cannot be changed at alater stage. Thus, if the user wants to change the image type, it isnecessary to re-read an original of the image data.

SUMMARY OF THE INVENTION

It is an object of the present invention to at least partially solve theproblems in the conventional technology.

According to an aspect of the present invention there is provided animage processing apparatus including a data receiving unit that receivesimage data; an extracting unit that extracts pieces of image datacorresponding to visually different image areas of an image of the imagedata received by the data receiving unit; a first storage unit thatstores therein the pieces of the image data extracted by the extractingunit; a second storage unit that stores therein a plurality of criteriafor identifying each of the image areas as one of processing areas thatare subjected to different image processing depending on an imagesegmentation mode for segmenting the image data into the processingareas; a mode receiving unit that receives a selection of the imagesegmentation mode from a user; a criterion selecting unit that selectsone of the criteria stored in the second storage unit based on the imagesegmentation mode selected by the user by using the mode receiving unit;an area identifying unit that identifies each of the image areas of thepieces of the image data stored in the first storage unit as one of theprocessing areas based on the criterion selected by the criterionselecting unit; and an image processing unit that performs imageprocessing associated with each of the processing areas on theprocessing areas identified by the area identifying unit.

According to another aspect of the present invention there is providedan image forming apparatus including a data receiving unit that receivesimage data; an extracting unit that extracts pieces of image datacorresponding to visually different image areas of an image of the imagedata received by the data receiving unit; a first storage unit thatstores therein the pieces of the image data extracted by the extractingunit; a second storage unit that stores therein a plurality of criteriafor identifying each of the image areas as one of processing areas thatare subjected to different image processing depending on an imagesegmentation mode for segmenting the image data into the processingareas; a mode receiving unit that receives a selection of the imagesegmentation mode from a user; a criterion selecting unit that selectsone of the criteria stored in the second storage unit based on the imagesegmentation mode selected by the user by using the mode receiving unit;an area identifying unit that identifies each of the image areas of thepieces of the image data stored in the first storage unit as one of theprocessing areas based on the criterion selected by the criterionselecting unit; and an image processing unit that performs imageprocessing associated with each of the processing areas on theprocessing areas identified by the area identifying unit.

According to still another aspect of the present invention there isprovided an image processing method implemented by an image processingapparatus including a first storage unit that stores therein pieces ofimage data corresponding to visually different image areas of an imageof original image data; and a second storage unit that stores therein aplurality of criteria for identifying each of the image areas as one ofprocessing areas that are subjected to different image processingdepending on an image segmentation mode for segmenting the image datainto the processing areas. The image processing method including firstreceiving including receiving image data; extracting the pieces of theimage data corresponding to the image areas from the image data receivedat the first receiving; storing the pieces of the image datacorresponding to the image areas extracted at the extracting in thefirst storage unit; second receiving including receiving a selection ofthe image segmentation mode from a user; identifying each of the imageareas as one of the processing areas based on the selection of the imagesegmentation mode received at the second receiving; and performing imageprocessing associated with each of the processing areas on theprocessing areas identified at the identifying.

According to still another aspect of the present invention there isprovided a computer program product comprising a computer usable mediumhaving computer readable program codes embodied in the medium that, whenexecuted, causes a computer to execute the above image processingmethod.

The above and other objects, features, advantages and technical andindustrial significance of this invention will be better understood byreading the following detailed description of presently preferredembodiments of the invention, when considered in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a multifunction peripheral (MFP) accordingto an embodiment of the present invention;

FIG. 2 is a schematic diagram for explaining a picture area and an edgearea according to the embodiment;

FIG. 3 is a block diagram of an area extracting unit shown in FIG. 1;

FIG. 4 is a block diagram of an area identifying unit shown in FIG. 3;

FIG. 5 is a block diagram of an output-format converting unit shown inFIG. 1;

FIG. 6 is a schematic diagram for explaining a configuration of imagedata converted by the output-format converting unit shown in FIG. 5;

FIG. 7 is a block diagram of an input-format converting unit shown inFIG. 1;

FIG. 8 is a schematic diagram illustrating criteria stored in acriterion storage unit, which indicates correspondence between signalswhen an image segmentation mode is a standard mode;

FIG. 9 is a schematic diagram illustrating criteria stored in thecriterion storage unit, which indicates correspondence between signalswhen the image segmentation mode is a text mode;

FIG. 10 is a schematic diagram illustrating processing contents ofprocessing performed on each area in each image processing mode;

FIG. 11 is a flowchart of a procedure of a process performed by the MFPshown in FIG. 1 from reading of an original to storing of image data ofthe original in an HDD; and

FIG. 12 is a flowchart of a procedure of a process from processing onthe image data stored in the HDD to printing of the image data by aplotter in the MFP shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention are explained in detailbelow with reference to the accompanying drawings. While the presentinvention is applied to an image forming apparatus in the followingembodiments, the present invention can be applied to devices other thanthe image forming apparatus.

In the following explanation, the image forming apparatus is assumed tobe a multifunction peripheral (MFP) having functions of a copier, afacsimile (FAX), a scanner, and a data transmission device thattransmits an input image (e.g., an image of an original read by thescanner or an image input by the printer or the FAX) to other devices.However, the image forming apparatus can be a device other than themultifunction peripheral.

FIG. 1 is a block diagram of an MFP 100 according to an embodiment ofthe present invention. The MFP 100 includes a scanner 101, a scannercorrecting unit 102, a compression processing unit 103, a controller104, a network interface card (NIC) 105, a hard disk drive (HDD) 106, anexpansion processing unit 107, a printer correcting unit 108, a plotter109, and an input device 110. The MFP 100 is connected to an externalpersonal computer (PC) terminal 130 via a network.

The HDD 106 is a storage unit and it is used to store image data,information contained in various signals, and the like. A device otherthan the HDD 106 can be employed as the storage unit to store variousdata. For example, typical storage units such as an optical disk, amemory card, and a random access memory (RAM) can be employed as thestorage unit.

A user uses the input device 110 for inputting various instructions ordata. That is, the user controls operations, i.e., selects functions,sets parameters etc., of the MFP 100 by using the input device 110.

Image data of an original acquired by the scanner 101 by scanning theoriginal is stored in the HDD 106. When performing a copy process, whichis one example of executable processes, the MFP 100 receives a selectionof an image segmentation mode from a user via the input device 110, andperforms processes to print out an image of the image data based on thereceived image segmentation mode.

The image segmentation mode is way of specifying a priority area wheneach area in an image of image data is identified as a text area, apicture area, and the like. That is, the image segmentation modespecifies, when a certain area of the image can be identified as boththe text area and the picture area, whether the area is to be identifiedas the text area or the picture area. The MFP 100 performs predeterminedimage processing with respect to each area identified based on the imagesegmentation mode. In other words, the image segmentation mode is usedfor segmenting the image of the image data into a plurality ofprocessing areas that are to be subjected to different image processing,respectively. It is assumed below that a standard mode and a text modecan be selected as the image segmentation mode.

In the text mode, an area that may contain text is preferentiallyextracted as a text edge area. That is, when a certain area may containtext, even if the area may also contain a picture and the like that canbe extracted as the picture area, that area is preferentially extractedas the text area.

In the picture mode, an area that may contain a picture ispreferentially extracted as the picture area. That is, when a certainarea may contain a picture, even if the area may also contain text thatcan be extracted as the text area, that area is preferentially extractedas the picture area.

When the MFP 100 performs the copy process, the scanner 101 opticallyreads an original, converts an analog signal obtained through opticalreading of the original into a digital signal (e.g., 600 dots per inch(dpi)), and outputs the digital signal as image data.

The scanner correcting unit 102 includes an area extracting unit 121 anda scanner γ unit 122. The scanner correcting unit 102 extracts imagedata from each of a text area, a line image area, a photograph area, andthe like of an image of the image data received from the scanner 101,and performs image processing such as a filtering process on RGB data ofthe input image data.

Specifically, the area extracting unit 121 extracts the image datacorresponding to visually different areas of the image of the inputimage data (linear reflectance data). The image data corresponding tothe areas can be extracted by using various methods, such as the methoddisclosed in Japanese Patent Application Laid-open No. 2003-259115.

More particularly, the area extracting unit 121 extracts image datacorresponding to two different areas, that is, an edge area and apicture area other than the edge area (e.g., a photograph area). Theedge area corresponds to an area in which an edge that may be an edge oftext is detected. The picture area corresponds to an area other than theedge area, for example, a photograph area and the like.

The area extracting unit 121 also extracts a color area from the imageof the input image data. The color area corresponds to an area in whichcolor content other than black content is drawn on a white background.

The area extracting unit 121 assigns a segmentation signal to each pixelof the input image data based on the extracted areas (e.g., the edgearea, the picture area, and the color area). The segmentation signalcontains information for identifying the areas. More particularly, thesegmentation signal contains 3-bit information containing a textseparation signal (2 bits) and a color area signal (1 bit). A type of anarea of each pixel can be identified from the contents of thesegmentation signal.

The text separation signal (2 bits) contains text information (1 bit)indicating whether a pixel corresponds to a text edge and pictureinformation (1 bit) indicating whether the pixel corresponds to thepicture area. Specifically, when no white background is detected as aresult of extracting a white area and a halftone-dot is detected as aresult of extracting a halftone-dot, which will be described later,information indicating the picture area is set in the pictureinformation.

The color area signal (1 bit) contains information indicating whetherthe pixel corresponds to the color area (in which color content otherthan black content is drawn on a white background).

FIG. 2 is a schematic diagram for explaining various areas in an imageof image data according to the embodiment. Input image data 201 isstored in the HDD 106 as stored image data. The area extracting unit 121extracts the image data corresponding to the picture area and the edgearea from the input image data 201. Then, image data corresponding tothe picture area and the edge area are stored in the HDD 106, i.e., inaddition to the stored image data.

When receiving a request of printing an image of the image data storedin the HDD 106, it is identified whether each pixel of the stored imagedata corresponds to a color-text-edge area, a black-text-edge area, orthe picture area based on the image segmentation mode input by a user atthe time of inputting the request.

The black-text-edge area is an area in which an edge of black text ispresent on a white background. The color-text-edge area is an area inwhich an edge of color text other than the black text is present on awhite background.

In the example shown in FIG. 2, an area 202 containing color text “newrelease” corresponds to both the edge area and the color area (althoughthe diagram is not color). When the text mode is selected as the imagesegmentation mode, the area 202 is identified as the color-text-edgearea, so that the text “new release” is processed as a color text edge.On the other hand, when the standard mode is selected as the imagesegmentation mode, the area 202 is identified as the picture area. Thus,a criterion for identifying the area is changed depending on whether thetext mode or the standard mode is selected as the image segmentationmode.

In the embodiment, whether an area is to be extracted as thecolor-text-edge area or the picture area is determined based on theimage segmentation mode selected by a user. However, it is applicable tomake such a determination based on the color-text-edge area and otherintermediate processes.

When the standard mode is selected as the image segmentation mode andthe text “new release” is thereby identified as a picture, and if thesize of the text is small, the readability of the determination could below. However, when the text mode is selected as the image segmentationmode as shown in FIG. 2, the text “new release” is identified as text,and a process suitable for the text is performed on all areas that maycontain text including the area containing the text “new release”.Therefore, the readability of the text “new release” in an output imagecan be increased.

Thus, when the stored image data is reprinted, a desired image can beoutput based on the selection of the image segmentation mode.

The area extracting unit 121 outputs image data corresponding to theedge area, image data corresponding to the picture area, the storedimage data, and the segmentation signal of each pixel of the storedimage data.

FIG. 3 is a detailed block diagram of the area extracting unit 121. Thearea extracting unit 121 includes a filter 321, an edge extracting unit322, a white-area extracting unit 323, a halftone-dot extracting unit324, a color identifying unit 325, and an area identifying unit 326.

The filter 321 is used for intensifying green (G) image data of theimage data received from the scanner 101 to extract an edge of text ofthe image data.

The edge extracting unit 322 includes a trinarizing unit 322 a, ablack-continuous-pixel detecting unit 322 b, a white-continuous-pixeldetecting unit 322 c, a neighboring-pixel detecting unit 322 d, and anisolated-pixel removing unit 322 e. In the embodiment, it is assumedthat the G image data is referred to when an edge of the text isextracted. However, other data or signals that represent shading, suchas brightness data, can be used instead of the G image data.

The text area is generally formed of only pixels having high densities(hereinafter, “black pixels”) and pixels having low densities(hereinafter, “white pixels”), and more particularly, edge portions oftext in the text area are formed of black continuous pixels and whitecontinuous pixels. Based on this fact, the black-continuous-pixeldetecting unit 322 b detects continuity of black pixels and thewhite-continuous-pixel detecting unit 322 c detects continuity of whitepixels. Then, the neighboring-pixel detecting unit 322 d detectsneighboring pixels of black continuous pixels and white continuouspixels, and the isolated-pixel removing unit 322 e removes isolatedpixels (pixels corresponding to a predetermined condition). The edgeextracting unit 322 then identifies the edge area based on results fromthe above units.

The white-area extracting unit 323 identifies an area in which contentis drawn on a white background as a white area, an area around darkblack text as the white area, and an area having a low density as anon-white area with respect to each image data.

The halftone-dot extracting unit 324 extracts halftone dots from animage of the image data, and identifies the extracted halftone dots as ahalftone-dot area.

The color identifying unit 325 includes a hue classifying unit 325 a, ac-memory 325 b, an m-memory 325 c, a y-memory 325 d, a w-memory 325 e,and a color-pixel identifying unit 325 f. The hue classifying unit 325 aclassifies pixels into hues of cyan, magenta, yellow, and white, andstores the pixels in the c-memory 325 b, the m-memory 325 c, they-memory 325 d, and the w-memory 325 e based on a result of theclassification. The color-pixel identifying unit 325 f identifies color(chromatic) pixels and black (achromatic) pixels of the image data basedon the information stored in the memories 325 b to 325 e.

The area identifying unit 326 comprehensively identifies an area of eachpixel. FIG. 4 is a detailed block diagram of the area identifying unit326. The area identifying unit 326 includes a text identifying unit 326a, a dilation processing unit 326 b, and a decoding unit 326 c.

The text identifying unit 326 a identifies a pixel of the image data asa text edge when the pixel corresponds to the edge area based on aresult from the edge extracting unit 322, does not correspond to thehalftone-dot area based on the result from the halftone-dot extractingunit 324, and corresponds to the white area based on a result from thewhite-area extracting unit 323. Otherwise, the text identifying unit 326a identifies the pixel as a non-text edge (i.e., the pixel is either apicture or a part of text).

The dilation processing unit 326 b performs OR operation on 8×8 blocksbased on a result from the text identifying unit 326 a, and thenperforms AND operation on 3×3 blocks based on the result from the textidentifying unit 326 a to dilate the text edge by four pixels. That is,when at least one of 8×8 pixels around a target pixel is identified asthe text edge, that the target pixel is assumed to be in the text edgearea, and then, when all of 3×3 pixels around the target pixel areidentified as the text edge area, the target pixel is identified as thetext edge. Then, the target pixel and four adjacent pixels, i.e., fivepixels in total, are identified as the text edge area.

The dilation processing unit 326 b outputs the result of the process asa text edge signal to the decoding unit 326 c. Because the dilationprocessing unit 326 b performs the process in the above manner, it ispossible to prevent blurring of the text area caused by fluctuation inresults of text identification.

The decoding unit 326 c outputs the text separation signal (a C/P signalin FIG. 4). The area identifying unit 326 outputs a color identificationresult as the color area signal (a B/C signal in FIG. 4). Thus,information corresponding to the text separation signal (2 bits for eachpixel) and the color area signal (1 bit for each pixel), i.e., 3 bits intotal, is output. In this manner, the segmentation signal containing thetext separation signal and the color area signal is output.

Returning to FIG. 1, the scanner γ unit 122 converts the image data (thestored image data, the image data corresponding to the edge area, andthe image data corresponding to the picture area) received from the areaextracting unit 121 from linear reflectance data to linear density data.

The compression processing unit 103 compresses 8-bit-based RGB imagedata obtained after scanner correction, the text separation signal (2bits), and the color area signal (1 bit), and outputs them to auniversal bus. The compressed image data, the text separation signal (2bits), and the color area signal (1 bit) are then sent to the controller104 via the universal bus. While the image data, the text separationsignal (2 bits), and the color area signal (1 bit) are compressed in theembodiment, if a bandwidth of the universal bus is sufficiently wide andthe capacity of the HDD 106 is sufficiently large, it is not necessaryto compress the image data and the signals.

The controller 104 includes a page memory 131, a compression-expansionprocessing unit 132, an output-format converting unit 133, a datainterface (I/F) unit 134, an input-format converting unit 135, and adevice I/F unit 136. The controller 104 outputs image data stored in theHDD 106 to the external PC terminal 130, and receives image data fromthe external PC terminal 130. The controller 104 also executes a processof inputting operations performed via the input device 110.

The device I/F unit 136 processes information received from the inputdevice 110. The device I/F unit 136 receives an input of the imagesegmentation mode via the input device 110. The device I/F unit 136 alsoreceives an input of an image processing mode input via the input device110.

The image processing mode is processing information about a readoriginal. The image processing mode is selected from the following threemodes: a text mode in which a process is performed with priority ontext; a standard mode in which a process is performed so that text andphotograph can be balanced with each other; and a photograph mode inwhich a process is performed with priority on photograph.

The controller 104 stores input image data in the HDD 106. Thecontroller 104 also stores bibliographic data of the input image data,such as an image size, and information contained in the text separationsignal (2 bits) and the color area signal (1 bit) in the HDD 106 inassociation with the input image data. If the controller 104 receivesinputs of the image segmentation mode and the image processing modetogether with the image data, the controller 104 can also store theinput modes in the HDD 106.

The page memory 131 temporarily stores therein the input image data, thetext separation signal (2 bits) and the color area signal (1 bit).

More particularly, the controller 104 stores compressed image datareceived from the compression processing unit 103 in the HDD 106. Then,when the compressed image data stored in the HDD 106 is reused, thecontroller 104 reads out the compressed image data from the HDD 106 tothe page memory 131.

The compression-expansion processing unit 132 expands the compressedimage data stored in the page memory 131 into the original image data,i.e., the 8-bit-based RGB image data, and outputs the 8-bit-based RGBimage data to the output-format converting unit 133.

The output-format converting unit 133 converts a color space of the RGBimage data into an sRGB color space that is a standard color space, andconverts a format of the RGB image data into a universal image formatsuch as a Joint Photographic Experts Group (JPEG) format or a Tag ImageFile Format (TIFF) format. The output-format converting unit 133receives the text separation signal (2 bits) and the color area signal(1 bit) corresponding to the input image data via thecompression-expansion processing unit 132.

FIG. 5 is a detailed block diagram of the output-format converting unit133. The output-format converting unit 133 includes a color convertingunit 501, a resolution converting unit 502, a TIF-format generating unit503, a JPG-format generating unit 504, a compression-format generatingunit 505, and a data I/F unit 506.

The color converting unit 501 converts the input RGB image data intopredetermined RGB image data. The resolution converting unit 502converts a pixel density of the converted RGB image data into apredetermined pixel density of 300 dpi, 200 dpi, or the like. In theembodiment, the pixel density is converted into 300 dpi.

Each of the TIF-format generating unit 503, the JPG-format generatingunit 504, and the compression-format generating unit 505 converts a fileformat of the image data, of which resolution has been converted, into acorresponding format. The compression-format generating unit 505 isdescribed in detail below.

The compression-format generating unit 505 includes a binarizing unit511, a binarized-image generating unit 512, a black-image generatingunit 513, a first resolution converting unit 514, a second resolutionconverting unit 515, a background-image generating unit 516, atext-image generating unit 517, and an image-file compositing unit 518.

The binarizing unit 511 outputs binarized image data in which the textarea and a non-text area are identified based on the level of the imagedensity, mask image data (2 bits), and black-text image data (1 bit),with respect to each pixel of the image data that is input by theresolution converting unit 502 after the image density of the image databeen converted.

The binarizing unit 511 binarizes the image data by using any methods.The binarizing unit 511 serially processes pixels in the first line ofthe image data one after the other and then serially processescontinuous lines one after the other in the same manner until the lastline of the image data. In the embodiment, the image data to beprocessed is assumed as the RGB image data. More particularly, it isassumed that the RGB image data is darkened as pixel values thereofincrease and lightened as the pixel values decrease.

The binarizing unit 511 receives the text separation signal (2 bits) andthe color area signal (1 bit) via the compression-expansion processingunit 132. Then, the binarizing unit 511 identifies whether each pixel ofthe received image data is either the text edge area or the other area.A correspondence between each pixel of the image data and the inputsignals (e.g., the text separation signal (2 bits) and the color areasignal (1 bit)) can be determined by using any known methods, andtherefore, detailed explanation thereof is omitted.

The binarizing unit 511 sets thresholds for binarizing image datacorresponding to the text edge area and image data corresponding to theother area, respectively, and switches over the thresholds depending onthe area to be processed. Parameters for the text edge area are set sothat the readability of text can be more assured compared to the otherarea.

The binarizing unit 511 binarizes image data corresponding to the textedge area and the other area by using the corresponding thresholds.Specifically, when at least one pixel values of a pixel of the input RGBimage data exceeds the threshold, the binarizing unit 511 identifies thepixel as black (ON), and, when all pixel values of a pixel of the inputRGB image data do not exceed the threshold, the binarizing unit 511identifies the pixel as white (OFF). For example, when the threshold fora pixel is set to such pixel values that R=128, G=120, and B=118, and ifa pixel of the input image data has such pixel values that R=121, G=121,and B=121, the binarizing unit 511 identifies the pixel as black. On theother hand, if a pixel of the input image data has such pixel valuesthat R=110, G=110, and B=110, the binarizing unit 511 identifies thepixel as white.

The reason why the thresholds are changed between the text edge area andthe other area is that processing contents need to be changed dependingon background colors. Specifically, if a single piece of image datacontains dark-colored text drawn on a colored background other than awhite background and light-colored text drawn on a white background, andthe text is subjected to the same image processing by using the samethreshold, the text on different-colored backgrounds cannot be uniformlyidentified as black (ON).

To prevent such a situation, the binarizing unit 511 changes thethresholds between the text edge area and the other area. Accordingly,the threshold for text on a white background and the threshold for texton a colored background other than the white background can bedifferentiated from each other, so that both light-colored text on thewhite background and text on the colored background can be identified asblack (ON). As a result, the image data can be properly binarized.

In the embodiment, although details will be described later, the textedge area of the image data to be binarized is subjected to an edgeenhancement process (a sharpening process) and the other area issubjected to image processing corresponding to the amount of edge.Therefore, the picture area is subjected to a smoothing process. At thistime, a background area of the colored background on which text is drawnis also subjected to the smoothing process, so that the image data canbe binarized properly.

The binarizing unit 511 generates mask image data (1 bit) for each pixelof the input image data. The mask image data (1 bit) indicates halftonedots and a colored background that is other than the white background.

Specifically, the binarizing unit 511 detects halftone dots from theimage data. For example, when a predetermined number of halftone-dotpatterns are detected in an area between a white pattern (i.e., awhite-colored area without other colors) and another white pattern, thebinarizing unit 511 identifies pixels in the halftone-dot patterns ashalftone dots. Furthermore, when a predetermined interval is detectedbetween one halftone-dot pattern and another halftone-dot pattern, thebinarizing unit 511 identifies pixels in the interval as non halftonedots. As a result, white-colored text on a dark-colored area of agradational black background can be identified as the non halftone dot.For example, the binarizing unit 511 identifies white-colored text on adark-colored area of a gradually-lightened background of image data asthe non halftone dot. The binarizing unit 511 also identifies adark-colored area of a gradually-darkened background of the image dataas the non halftone-dot because halftone-dot patterns can hardly bedetected in the dark-colored area. The binarizing unit 511 alsoidentifies dark-colored text on a light-colored background of the imagedata as the non halftone-dot because halftone-dot patterns can hardly bedetected in the dark-colored text.

Thus, because text is generally drawn on the white background andthereby halftone-dot patterns exist only at around an edge of the texton the white background, it is possible to prevent the text on the whitebackground from being erroneously identified as a halftone-dot area.

While the pattern matching is performed between the white-colored areaand the area other than the white-colored area in the embodiment, it isapplicable to individually perform the pattern matching for each ofY-component, M-component, and C-component. If halftone-dots are detectedindividually for each of the Y-component, the M-component, and theC-component, because ink is composed of these components, dotreproducibility of the ink can be accurately detected.

The binarizing unit 511 performs, based on the fact that the text areais relatively dark and the area around the text is relatively light, aprocess of identifying an area that is lighter than the text area anddarker than an area around the text as a gray area having a density ofmiddle level. In the process of identifying the gray area, the whitebackground corresponding to a white pixel obtained after N-thdigitization (N is an arbitrary numeric values; for example, eight) isused.

Generally, an area containing text (i.e., the text area) is formed ofonly a dark-colored pixel area and a light-colored pixel area (e.g., awhite background), so that the binarizing unit 511 does not generallydetect the gray area from the text area. On the other hand, the picturearea (e.g., the photograph area) separated from the text area contains aplurality of tones of colors, so that the binarizing unit 511 detects anarea having a density of middle level as the gray area. In theembodiment, the binarizing unit 511 identifies an area as the gray areauntil the number of white pixels among neighboring pixels of the areaexceeds a predetermined threshold.

The binarizing unit 511 also detects a dark-colored pixel as a graypixel. When a predetermined number or more of black pixels are continuedin the gray area, the binarizing unit 511 detects these pixels asnon-gray pixels. Then, the binarizing unit 511 identifies an area formedof the gray pixels as the gray area. As a result, the binarizing unit511 can detect white-colored text on a black background as a non-grayarea.

In this manner, the binarizing unit 511 generates the mask image dataindicating whether a pixel corresponds to the halftone dot or the grayarea for each pixel of the image data.

The binarizing unit 511 includes a text identifying unit (not shown)that identifies a black text area and a color text area. Then, thebinarizing unit 511 outputs for each pixel, as a result of all the aboveprocesses, 3-bit data corresponding to the binarized image (binarizedareas) for identifying areas of the image data depending on the imagesegmentation mode, the mask image data (the halftone-dot area or thegray area), and the black text area.

The text identifying unit identifies whether an area is the color textarea or the black text area. The identification can be performed byusing any known methods.

The text identifying unit performs logical operation on the textseparation signal (2 bits) and the color area signal (1 bit) for eachpixel of the image data. When the pixel corresponds to the text edgearea and does not correspond to the color area, the text identifyingunit outputs the pixel as a black-text-edge area.

A tip portion of text of the image data is generally thin, so that itcan hardly be identified as a halftone dot (i.e., it can hardly beidentified as the non-text area). If the tip portion of the text isidentified as the text edge area while a middle portion of the text isidentified as the halftone-dot area, the whole text after a black-textidentification process results in like incomplete text, resulting indegraded visual quality of the text. However, in the embodiment, becausethe MFP 100 performs the processes as described above, it is possible toprevent the middle portion of the text from being erroneously identifiedas the halftone-dot area. As a result, the degradation in visual qualityof the text can be prevented.

The binarized-image generating unit 512 performs a Modified ModifiedRelative Element Address Designate codes (MMR) compression that is alossless compression on the binarized image data and the mask imagedata. The black-image generating unit 513 performs the MMR compressionthat is a lossless compression on the black-text image data.

FIG. 6 is a schematic diagram for explaining a configuration of imagedata converted by the output-format converting unit 133. The binarizingunit 511 generates the black-text image data, the mask image data, andthe binarized image data from the input image data 201.

The first resolution converting unit 514 and the second resolutionconverting unit 515 perform a resolution conversion on the image data togenerate image data having low resolution (e.g., 150 dpi).

The background-image generating unit 516 performs a lossy compression(e.g., JPG compression) to compress image data that is not masked by themask image data and is part of the binarized image data output by thebinarizing unit 511 into image data of an area formed of pixels havingpredetermined pixel values to be white.

The text-image generating unit 517 performs a lossy compression (e.g.,JPG compression) to compress the image data other than the binarizedimage data into image data formed of pixels having predeterminedconstant pixel values.

In the embodiment, image data of a background image is converted intoimage data formed of pixels having predetermined constant pixel valuesso that compressibility can be increased. Image data of a backgroundarea in text image data is also converted into image data formed ofpixels having predetermined constant pixel values so thatcompressibility can be increased.

In the resolution conversion performed by the resolution converting unit502, a resolution of a text image need not be set as high as that of abackground image. Therefore, the resolution of the text image can be setto, for example, about 75 dpi. When the text mode is selected as theimage processing mode, the resolution converting unit 502 generates animage file in JPG format by setting the resolution of each of thebackground image and the text image to 75 dpi. The reason why theresolution of the text image can be decreased is that the resolution ofthe text image is assured by the MMR compression that is a losslesscompression, and thereby, tone degradation because of decrease in theresolution of the JPG image does not cause problems with the text image.Thus, in the MFP 100, a file size can be reduced by decreasing theresolution of the text image. While the file size is reduced bydecreasing the resolution of the text image in the embodiment, the filesize can be reduced by decreasing image quality, such as the number ofgradations of the image data, other than the resolution.

In the HDD 106, the image processing mode is stored as the bibliographicdata of the image data in association with the stored image data. If thetext mode is selected as the image processing mode, compressibility ofimage data corresponding to all the text areas in the stored image datacan be increased.

In the embodiment, a background image is generated by superimposing themask image on the image of the stored image data, and a text image isgenerated by superimposing the binarized image on the image of thestored image data. In some cases, both the text image and the backgroundimage contain the same information. The reason why the same informationmay be redundantly contained in both the text image and the backgroundimage is that the information is necessary when the input-formatconverting unit 135 switches over processing contents of imageprocessing depending on the image segmentation mode.

The background-image generating unit 516 and the text-image generatingunit 517 perform JPG compression by using quantization tables havingdifferent characteristics, respectively. The JPG compression can beperformed by using known techniques, for example, a method disclosed inJapanese Patent Application Laid-open No. 2005-303979.

Specifically, the background-image generating unit 516 and thetext-image generating unit 517 perform the JPG compression by clippingout image data in units of block (e.g., in units of 8×8 pixels) and thenperforming discrete cosine transform (DCT) to represent the clipped outDCT block data in frequency space.

At this time, a quantization process by which compression level isdetermined is performed by using a different standard quantization tablefor each of Y-component and CbCr component.

A quantization table value Q′ij actually used in the quantizationprocess is calculated by using a quality factor (qf) with respect to astandard quantization table value Qij. The qf is set to a value in arange from 0 to 100. When the qf is smaller than 50, the quantizationtable value Q′ij is calculated by the following Equation (1):

Q′ij=Qij/qf  (1)

When the qf is equal to or larger than 50, the quantization table valueQ′ij is calculated by the following Equation (2):

Q′ij=Qij×(100−qf)/50  (2)

A general standard quantization table is generated based on the factthat the human eye is sensitive to low-frequency waves and insensitiveto high-frequency waves. Furthermore, in the general standardquantization table, because color information is less identifiedcompared to brightness information, more amount of frequencies are cutoff for the color information compared to the brightness information.

In the embodiment, however, the background-image generating unit 516performs the quantization process by using the qf of about 20 to 30 tocompress image data. Therefore, if the general standard quantizationtable is used, block noise is more likely to occur. Particularly, theblock noise for each unit of the JPG compression (e.g., each block of8×8 pixels) is largely affected by a value of a DC component thatrepresents an average density of each block. To reduce the block noisefor each unit of the JPG compression, such a standard quantization tablethat can retain values of DC components of a brightness difference and acolor difference is employed in the embodiment. The standardquantization table in this case can be any known standard quantizationtables, and therefore, detailed explanation thereof is omitted. Forexample, when the qf is set to 25, a quantization table to be actuallyused in the quantization process is obtained through a calculation basedon Equation (1) and the standard quantization table. Then, thebackground-image generating unit 516 performs the quantization processby using the obtained quantization table.

When the text-image generating unit 517 performs the JPG compression byusing the general standard quantization table, color mixture may occur.To prevent the color mixture, the text-image generating unit 517 usessuch a standard quantization table that can retain the whole frequenciesof a color difference component. The standard quantization table in thiscase can be any known standard quantization tables, and therefore,detailed explanation thereof is omitted. Then, a quantization table tobe actually used in the quantization process is obtained based on thestandard quantization table and a value obtained through a calculationusing the qf set to 20. The brightness component in the obtainedquantization table is not practically important because the resolutionof the text image is determined by the resolution obtained through theMMR compression. The text-image generating unit 517 performs thequantization process by using the obtained quantization table.

Thus, in the quantization table used for the background image, the DCcomponents of a brightness difference and a color difference areretained, so that the block noise in a smooth area in an image can bereduced. On the other hand, in the quantization table for the textimage, the color difference component is retained by retaining higherfrequency components compared to the quantization table for thebackground image that retains the brightness difference component, sothat color mixture in each block of 8×8 pixels can be prevented.

In other words, in the quantization table for the background image,priority is given to the DC components of both the brightness differenceand the color difference. On the other hand, in the quantization tablefor the text image, priority is given to frequencies of the colordifference while a standard brightness component is maintained.

The image-file compositing unit 518 composites four pieces of image dataoutput by the binarized-image generating unit 512 (through the MMRcompression), the black-image generating unit 513 (through the MMRcompression), the background-image generating unit 516 (through the JPGcompression), and the text-image generating unit 517 (through the JPGcompression) to generated one piece of image data. At this time, a fileformat can be a universal file format (e.g., portable document format(PDF)). The image-file compositing unit 518 can output the four piecesof the image data separately to the input-format converting unit 135.

The data I/F unit 506 outputs image data in a format to be output to theNIC 105 or outputs the four pieces of the image data to be output to theinput-format converting unit 135.

Returning to FIG. 1, the data I/F unit 134 outputs the image datareceived from the output-format converting unit 133 to the NIC 105 or tothe input-format converting unit 135.

The input-format converting unit 135 converts a format of the image datainto an arbitrary format and outputs the image data in the convertedformat.

FIG. 7 is a block diagram of the input-format converting unit 135. Theinput-format converting unit 135 includes a TIF-format expanding unit1801, a JPG-format expanding unit 1802, a compression-format expandingunit 1803, and an output selecting unit 1804.

Each of the TIF-format expanding unit 1801, the JPG-format expandingunit 1802, and the compression-format expanding unit 1803 expands imagedata into bitmap data in each corresponding format.

The output selecting unit 1804 selects one format from the three formatsexpanded by the TIF-format expanding unit 1801, the JPG-format expandingunit 1802, and the compression-format expanding unit 1803, and outputsthe image data in the selected format. At the same time, the outputselecting unit 1804 coverts RGB data of the image data into YMCBk imagedata.

For example, when the input image data is in TIF format, the TIF-formatexpanding unit 1801 expands the image data into bitmap data. When theinput image data is in JPG format, the JPG-format expanding unit 1802expands the image data into bitmap data. When the input image data is incompressed format, the compression-format expanding unit 1803 expandsthe image data into bitmap data.

The compression-format expanding unit 1803 includes an image-fileexpanding unit 1811, a black-image expanding unit 1812, abinarized-image expanding unit 1813, a background-image expanding unit1814, a text-image expanding unit 1815, an image-file compositing unit1816, and a composition selecting unit 1817. The compression-formatexpanding unit 1803 performs processing on the four pieces of image datareceived from the output-format converting unit 133.

The image-file expanding unit 1811 outputs each of the four files in animage data file generated by the compression-format generating unit 505(see FIG. 5) as image data to corresponding one of the black-imageexpanding unit 1812, the binarized-image expanding unit 1813, thebackground-image expanding unit 1814, and the text-image expanding unit1815.

The binarized-image expanding unit 1813 expands the MMR-compressed imagedata into bitmap data of the binarized image and the mask image.

The black-image expanding unit 1812 expands the MMR-compressed imagedata into bitmap data of the black text image.

The background-image expanding unit 1814 expands image data of thebackground image in the JPG format into bitmap data. The text-imageexpanding unit 1815 expands image data of the text image in the JPGformat into bitmap data.

The composition selecting unit 1817 selects an expansion method and acomposition method based on the image segmentation mode received fromthe page memory 131.

The image-file compositing unit 1816 composites the four pieces of theexpanded bitmap data to generate one piece of bitmap data by using thecomposition method selected by the composition selecting unit 1817.

When the composition selecting unit 1817 selects the standard mode asthe image segmentation mode, and when there is image data of a binarizedimage that does not contain a mask image, the binarized-image expandingunit 1813 outputs image data of a corrected binarized image. Uponreceiving the image data of the corrected binarized image from thebinarized-image expanding unit 1813, the image-file compositing unit1816 outputs pixels of image data received from the text-image expandingunit 1815. Upon receiving image data other than the image data of thecorrected binarized image from the binarized-image expanding unit 1813,the image-file compositing unit 1816 outputs pixels of image datareceived from the background-image expanding unit 1814. When a resultreceived from the black-image expanding unit 1812 indicates black text,the image-file compositing unit 1816 outputs black pixels as pixels ofimage data. Then, image data of one image is generated by the outputpixels. The resolutions of the text area and the non-text areacorrespond to the resolutions of the binarized image.

When the composition selecting unit 1817 selects the text mode as theimage segmentation mode, and when there is image data of a binarizedimage, the binarized-image expanding unit 1813 outputs image data of acorrected binarized image. Upon receiving the image data of thecorrected binarized image, the image-file compositing unit 1816 outputspixels of image data received from the text-image expanding unit 1815.When the image data received from the binarized-image expanding unit1813 is not the corrected binarized image, the image-file compositingunit 1816 outputs pixels of image data received from thebackground-image expanding unit 1814. At this time, because informationabout a text image is contained in a mask image (a background image) atthe boundary between the corrected binarized image and the mask image(i.e., information about text on the background image is mixed due toimage compression), image data in a boundary area is replaced with imagedata of a surrounding image. When a result received from the black-imageexpanding unit 1812 corresponds to black text, the image-filecompositing unit 1816 outputs black pixels as pixels of image data.Then, image data of one image is generated by the output pixels. Theresolutions of the text area and the non-text area correspond to theresolution of the binarized image.

In the example shown in FIG. 6, when the standard mode is selected asthe image segmentation mode, the text “new release” is identified as apicture, so that if the size of the text “new release” is small, thereadability of the text in an output image may be decreased. On theother hand, when the text mode is selected as the image segmentationmode, the text “new release” is identified as text, so that the text canbe subjected to image processing suitable for text. As a result, thereadability of the text in an output image can be increased.

In this manner, image data is generated based on the image segmentationmode selected by a user and results of processes of identifying areas ofthe image of the image data. Therefore, a desired image data can begenerated according to user's need. The same processes can be appliedwhen generating image data to be displayed on a monitor instead of theimage data to be printed out on a paper.

The generated image data is compressed by the compression-expansionprocessing unit 132, and then stored in the HDD 106 in association withvarious signals or output to the expansion processing unit 107 with thevarious signals via the universal bus so that an image of the image datacan be printed out.

Returning to FIG. 1, the controller 104 outputs the image data stored inthe HDD 106 to the expansion processing unit 107 via the universal bus.

The expansion processing unit 107 expands the compressed image data intothe original 8-bit-based RGB image data, the text separation signal (2bits), and the color area signal (1 bit), and then outputs the expandeddata and signals to the printer correcting unit 108. The image data tobe stored in the expansion processing unit 107 can be image dataextracted with respect to each area and stored in the HDD 106 or imagedata composited by the input-format converting unit 135. In thefollowing description, it is assumed that the image data extracted withrespect to each area and stored in the HDD 106 is input in the expansionprocessing unit 107.

The printer correcting unit 108 includes a halftone processing unit 141,a printer γ unit 142, a color-correction processing unit 143, anedge-amount detecting unit 144, a criterion storage unit 145, aselecting unit 146, and a filtering processing unit 147. The printercorrecting unit 108 performs a correction process on the image data.

The criterion storage unit 145 stores therein a criterion used forconverting the text separation signal (i.e., the text information (1bit) indicating whether a pixel corresponds to a text edge and thepicture information (1 bit) indicating whether the pixel corresponds tothe picture area) and the color area signal (1 bit) into a text-edgearea signal.

FIG. 8 is a schematic diagram illustrating criteria stored in thecriterion storage unit 145, which indicates correspondence betweensignals when the image segmentation mode is the standard mode. Forexample, a record 1901 indicates that when a pixel is identified as boththe edge area and the picture area in the standard mode, the pixel isresultantly identified as the other (picture) area regardless of aresult about the color area. As a result, the text-edge area signal isset as “NO”.

FIG. 9 is a schematic diagram illustrating criteria stored in thecriterion storage unit 145, which indicates correspondence betweensignals when the image segmentation mode is the text mode. For example,a record 2001 indicates that when a pixel is identified as both the edgearea and the picture area, the pixel is resultantly identified as thecolor-text-edge area regardless of a result about the color area. As aresult, the text-edge area signal is set as “YES”.

The selecting unit 146 converts the text separation signal (2 bits) andthe color area signal (1 bit) into the text-edge area signal (1 bit)based on the correspondence stored in the criterion storage unit 145 andthe image segmentation mode input by the user.

In other words, the selecting unit 146 generates the text-edge areasignal (1 bit) that is used for identifying the color-text-edge area andthe black-text-edge area based on the text separation signal and thecolor area signal that are used for identifying the edge area, thepicture area, and the color area.

The filtering processing unit 147 switches over processing contents of afiltering process to be performed on each pixel based on the pictureinformation (1 bit) that indicates whether the pixel corresponds to thepicture area and is contained in the text separation signal (2 bits),and the text-edge area signal (1 bit). Specifically, the filteringprocessing unit 147 performs an edge enhancement process (a sharpeningprocess) on the text edge area (both the black-text-edge area and thecolor-text-edge area are contained) so that the readability of text canbe increased.

The filtering processing unit 147 performs a smoothing process or theedge enhancement process (the sharpening process) on the color area suchas the photograph area based on an edge amount that indicates asteeply-changed density of the image data. An edge corresponding to thesteeply-changed density is enhanced so that the readability of textcontained in photograph, graphics, or graphs can be increased. In thetext edge area, thresholds used for binarization can be changed betweenthe color-text-edge area and the black-text-edge area in considerationof the color area.

The color-correction processing unit 143 converts RGB image data intoYMCBk image data, and replaces image data of an area that corresponds tothe text-edge area signal but does not correspond to the color areasignal into black (Bk) monochrome data of black text.

More particularly, the color-correction processing unit 143 converts RGBimage data of an area other than the black-text-edge area into CMY imagedata by using a first-order masking method for adjusting density or thelike. Then, the color-correction processing unit 143 generates Bk databy performing an under color removal (UCR) process on an area common toC data, M data, and Y data so that color reproducibility of the imagedata can be improved, and outputs the CMYBk data.

If black text in the black-text-edge area is colored because scanningpositions of RGB image data scanned by the scanner 101 are shifted, orif color shift occurs on YMCBk image data when the YMCBk image data isprinted out by the plotter 109, the readability of the text decreases.To prevent such a situation, the color-correction processing unit 143outputs a signal corresponding to the brightness as Bk monochrome datafor the black-text-edge area (i.e., the Y data, the M data, and the Cdata are pieces of data that are not printed out).

The printer γ unit 142 performs a γ correction process on the image databased on the γ characteristics of the plotter 109. In the embodiment,the printer γ unit 142 selects γ for the color-text-edge area and theblack-text-edge area so that contrast in these areas can be intensified,and selects γ for the other area (i.e., the picture area) so thatcharacteristics of input data can be substantially maintained, based onthe γ characteristics. Then, the printer γ unit 142 performs the γcorrection process by using the selected γ characteristics.

The edge-amount detecting unit 144 detects the steeply-changed densityof the image data as the edge amount.

The halftone processing unit 141 performs a quantization process such asa dithering process or an error diffusion process on the image data tocorrect tone of the image data. In other words, the halftone processingunit 141 performs a correction process or a tone conversion processbased on the tone characteristics of the plotter 109. The toneconversion process in the embodiment corresponds to a process forconverting the 8-bit-based image data into 2-bit image data through theerror diffusion process or the dithering process.

In the embodiment, the halftone processing unit 141 performs thequantization process such as the dithering process based on the tonecharacteristics of the plotter 109 or the edge amount and the imagesegmentation mode input by a user. In the quantization process, thecolor-text-edge area and the black-text-edge area are subjected to aprocess that gives priority to the resolution to increase sharpness oftext, and the other area (i.e., the picture area) is subjected to aprocess that gives priority to the tone. As a result, the readability ofthe text can be increased.

FIG. 10 is a schematic diagram illustrating processing contents ofprocessing performed on each area in each image processing mode. Theprocessing contents of the processing performed on each area are changeddepending on whether the image segmentation mode is the standard mode,the text mode, or the photograph mode. In the example shown in FIG. 10,the processing contents in, for example, fields 2101 and 2102 aredifferent from those set for the standard mode.

Returning to FIG. 1, the plotter 109 functions as a printing unit thatprints out an image of image data on a transfer sheet by performing alaser-beam writing process. Specifically, the plotter 109 draws a latentimage of 2-bit image data on a photosensitive element, performs an imageforming process and an image transfer process on the latent image withtoner, and forms a copy image of the image data on a transfer sheet.

The NIC 105 transmits and receives data, e.g., image data, to and fromthe external PC terminal 130.

When the MFP 100 functions as a transmission scanner that transmitsimage data to the external PC terminal 130 via a network, the image datais firstly sent to the controller 104 via the universal bus. Then, thecontroller 104 performs a color conversion process, a tone process, aformat process, and the like on the image data. In the tone process, thecontroller 104 performs a tone conversion process corresponding to themode in which the MFP 100 functions as the transmission scanner. In theformat process, the controller 104 converts a format of the image datainto a universal image format such as JPG format or TIF format. Then,the controller 104 transmits the image data to the external PC terminal130 via the NIC 105.

When the MFP 100 functions as a printer that prints out an image of datareceived from the external PC terminal 130 via the network, thecontroller 104 analyzes the image and a command indicating a printinstruction in the data received from the external PC terminal 130 viathe NIC 105. Then, the controller 104 expands the data into printablebitmap data as image data, compresses the expanded image data, and thenstores therein the compressed image data. The stored image data is thenwritten to the HDD 106 that is a large capacity storage unit as needed.When the image data is written to the HDD 106, bibliographic data of theimage data is also written to the HDD 106.

A process procedure for outputting the image data received from theexternal PC terminal 130 to the plotter 109 is described below. Acentral processing unit (CPU) (not shown) analyzes a command instructedby the external PC terminal 130, and writes the command in the pagememory 131. Upon receiving the image data, the data I/F unit 134 outputsthe image data to the input-format converting unit 135. Then, theinput-format converting unit 135 expands the image data into bitmapdata, and the compression-expansion processing unit 132 compresses theimage data. The image data is written to the page memory 131, and thenstored in the HDD 106. The image data is expanded by the input-formatconverting unit 135 into normal image data in JPG format or TIF format.

The controller 104 sends the image data stored in the HDD 106 to theexpansion processing unit 107 via the universal bus. The expansionprocessing unit 107 expands the compressed image data into the original8-bit-based image data, and then sends the expanded image data to theprinter correcting unit 108. When the input image data is RGB imagedata, the printer correcting unit 108 causes the color-correctionprocessing unit 143 to convert the RGB image data into YMCBk image data.Then, each color data of the YMCBk image data is subjected to the γcorrection process, the halftone process, and the like such that thecorrection process, the tone conversion process, and the like areperformed based on the tone characteristics of the plotter 109. In thetone conversion process at this time, the 8-bit-based image data isconverted into 2-bit image data through the error diffusion process orthe dithering process. Then, the plotter 109 draws a latent image of2-bit image data on a photosensitive element, performs an image formingprocess and an image transfer process on the latent image with toner,and forms a copy image of the image data on a transfer sheet.

In the MFP 100, the scanner 101 reads an original, converts image dataof the read original into digital data, and segments an image of theimage data into a plurality of areas based on characteristics of eacharea of the image. Then, various image processing is performed on theimage data with respect to each area containing a target pixel based ona result of identifying a type of each area. As a result, image qualityof an output image can be largely improved.

A process performed by the MFP 100 from reading of an original tostoring of image data of the original in the HDD 106 is described below.FIG. 11 is a flowchart of a procedure of a process performed by the MFP100 from reading of an original to storing image data of the original inthe HDD 106.

The scanner 101 scans an original and generates image data of theoriginal (Step S2201).

The area extracting unit 121 of the scanner correcting unit 102 extractsimage data corresponding to visually different areas of an image of theimage data of the original (Step S2202). Then, the area extracting unit121 outputs the segmentation signal and the color area signal generatedfor each pixel of the image data based on the extracted areas. Theextracted areas can be the edge area, the picture area (e.g., thephotograph area) other than the edge area, and the color area.

The scanner γ unit 122 converts image data (the stored image data, theimage data corresponding to the edge area, and the image datacorresponding to the picture area) from linear reflectance data tolinear density data (Step S2203).

The compression processing unit 103 then compresses the image data (thestored image data, the image data corresponding to the edge area, andthe image data corresponding to the picture area) (Step S2204).

The controller 104 stores the image data in the HDD 106 (Step S2205).

Thus, the image data corresponding to the extracted areas are stored inthe HDD 106.

A process from processing on the image data stored in the HDD 106 toprinting of the image data by the plotter 109 in the MFP 100 isdescribed below. FIG. 12 is a flowchart of a procedure of a process fromprocessing on the image data stored in the HDD to printing of the imagedata by the plotter 109 in the MFP 100.

The expansion processing unit 107 receives the image data from the HDD106, from the controller 104 (i.e., the stored image data, the imagedata corresponding to the edge area, and the image data corresponding tothe picture area), the text separation signal, and the color areasignal, and then expands the image data (Step S2301). The printercorrecting unit 108 receives inputs of the image processing mode and theimage segmentation mode from the controller 104. The image processingmode and the image segmentation mode are input via the input device 110.

The selecting unit 146 selects the text-edge area signal (1 bit) basedon the text separation signal (2 bits), the color area signal (1 bit),the correspondence stored in the criterion storage unit 145, and theimage segmentation mode input by a user (Step S2302). Based on theselected text-edge area signal (1 bit), whether each area is the textarea can be identified.

The filtering processing unit 147 performs a predetermined filteringprocess on each area based on the picture information (1 bit), whichindicates whether the pixel corresponds to the picture area and iscontained in the text separation signal (2 bits), and the text-edge areasignal (1 bit). Then, the color-correction processing unit 143, theprinter γ unit 142, and the halftone processing unit 141 performpredetermined image processing, which is set for each area, on each areaidentified by the text-edge area signal (1 bit) and the color areasignal (Step S2303).

Then, the plotter 109 prints out an image of the above processed imagedata (Step S2304).

In this manner, the MFP 100 can perform different image processingdepending on the input image processing mode and the image segmentationmode every time a process such as a printing process is performed on theimage data stored in the HDD 106. Therefore, it is possible to performimage processing suitable for use purpose of the image data.

Furthermore, in the MFP 100, image data of read original is stored inthe HDD 106 in association with image data of each area of the original,such as the black-text area or the picture area. The MFP 100 performsprocesses suitable for each area depending on the image processing modeand the image segmentation mode input by the user, and then performs theprinting process. Therefore, it is not necessary to read the originalevery time the modes are changed. As a result, operability can beimproved. Furthermore, it is not necessary to perform a process forextracting the areas, which needs to be performed every time theoriginal is read, so that a processing speed can be increased. Moreover,the image data can be printed out under a desired condition in a propermanner, users' usability can be enhanced.

The MFP 100 is configured to enable a user to select an identificationcriterion, for example, whether to give priority to text or picture.Therefore, desired image data can be generated.

The hardware configuration of the controller 104 of the MFP 100 isdescribed below. The controller 104 includes the CPU, a north bridge(NB), a system memory (MEM-P), a south bridge (SB), and a local memory(MEM-C), although they are not shown. The scanner correcting unit 102,the compression processing unit 103, the printer correcting unit 108,and the expansion processing unit 107 can be mounted inside theapplication specific integrated circuit (ASIC) (not shown) connected tothe controller 104. In this situation, the controller 104 and the ASICneed to be connected via a PCIe (PCI Express). The MEM-P includes a readonly memory (ROM) (not shown) and a random access memory (RAM) (notshown).

The CPU entirely controls the MFP 100, includes a chipset accommodatingthe NB, the MEM-P, and the SB, and is connected to other units via thechipset.

The NB is a bridge for connecting the CPU to the MEM-P, the SB, and thePCIe. The NB includes a memory controller (not shown) and a PCIe master(not shown). The memory controller controls reading and writing of datato the MEM-P.

The MEM-P is a system memory used as a memory for storing computerprograms and data, a memory for loading the computer programs and data,and a memory for drawing data by a printer. The MEM-P includes the ROMand the RAM. The ROM is a read only memory used for storing computerprograms and data. The RAM is a writable and readable memory thatfunctions as the page memory 131 and is used for memories for loadingthe computer programs and data and for drawing data by a printer.

The ASIC is an integrated circuit (IC) that includes hardware elementsfor image processing and performs image processing.

An image processing programs to be executed by the ASIC or thecontroller 104 of the MFP 100 is stored in a storage medium such as theROM for distribution.

The image processing programs to be executed by the MFP 100 can bestored, for distribution, in other computer readable recording mediasuch as a CD-ROM, a flexible disk (FD), a CD-R, or a digital versatiledisk (DVD) in an installable file format or a computer-executable fileformat.

The image processing programs to be executed by the MFP 100 can also bestored in a computer connected to the MFP 100 via a network such as theInternet such that the image processing programs can be downloaded viathe network. Furthermore, the image processing programs can be providedor distributed via the network such as the Internet.

The image processing programs has a module configuration including theabove units. As the actual hardware configuration, when the CPU(processor) reads and executes the image processing programs from theROM, the above units are loaded on a main memory and generated on themain memory.

According to one aspect of the present invention, an image processingapparatus stores image data that contains visually different areas,identifies the areas as processing areas based on a image segmentationmode set by a user, and performs image processing on each processingarea based on the image segmentation mode set by the user. Therefore, itis possible to output desired image data through processingcorresponding to user's need without inputting of the image data everytime the image data is output. Thus, user's usability can be enhanced.

Although the invention has been described with respect to specificembodiments for a complete and clear disclosure, the appended claims arenot to be thus limited but are to be construed as embodying allmodifications and alternative constructions that may occur to oneskilled in the art that fairly fall within the basic teaching herein setforth.

1. An image processing apparatus comprising: a data receiving unit thatreceives image data; an extracting unit that extracts pieces of imagedata corresponding to visually different image areas of an image of theimage data received by the data receiving unit; a first storage unitthat stores therein the pieces of the image data extracted by theextracting unit; a second storage unit that stores therein a pluralityof criteria for identifying each of the image areas as one of processingareas that are subjected to different image processing depending on animage segmentation mode for segmenting the image data into theprocessing areas; a mode receiving unit that receives a selection of theimage segmentation mode from a user; a criterion selecting unit thatselects one of the criteria stored in the second storage unit based onthe image segmentation mode selected by the user by using the modereceiving unit; an area identifying unit that identifies each of theimage areas of the pieces of the image data stored in the first storageunit as one of the processing areas based on the criterion selected bythe criterion selecting unit; and an image processing unit that performsimage processing associated with each of the processing areas on theprocessing areas identified by the area identifying unit.
 2. The imageprocessing apparatus according to claim 1, wherein the extracting unitincludes a edge extracting unit that extracts an edge area from theimage data; and a color extracting unit that extracts a color areahaving a predetermined color from the image data, the second storageunit stores therein a plurality of criteria based on correspondence ofeach of the image areas with the edge area and the color area, and thearea identifying unit identifies each of the image areas as one of theprocessing areas based on the criterion selected by the criterionselecting unit.
 3. The image processing apparatus according to claim 2,wherein the second storage unit stores therein a first criterion foridentifying an image area corresponding to the edge area as a processingarea to be subjected to image processing for text and a second criterionfor identifying an image area corresponding to both the edge area andthe color area as a processing area to be subjected to image processingfor text.
 4. The image processing apparatus according to claim 1,further comprising a display processing unit that displays image datacontaining image data corresponding to a text area among the image areasafter corresponding image processing is performed.
 5. An image formingapparatus comprising: a data receiving unit that receives image data; anextracting unit that extracts pieces of image data corresponding tovisually different image areas of an image of the image data received bythe data receiving unit; a first storage unit that stores therein thepieces of the image data extracted by the extracting unit; a secondstorage unit that stores therein a plurality of criteria for identifyingeach of the image areas as one of processing areas that are subjected todifferent image processing depending on an image segmentation mode forsegmenting the image data into the processing areas; a mode receivingunit that receives a selection of the image segmentation mode from auser; a criterion selecting unit that selects one of the criteria storedin the second storage unit based on the image segmentation mode selectedby the user by using the mode receiving unit; an area identifying unitthat identifies each of the image areas of the pieces of the image datastored in the first storage unit as one of the processing areas based onthe criterion selected by the criterion selecting unit; and an imageprocessing unit that performs image processing associated with each ofthe processing areas on the processing areas identified by the areaidentifying unit.
 6. An image processing method implemented by an imageprocessing apparatus including a first storage unit that stores thereinpieces of image data corresponding to visually different image areas ofan image of original image data; and a second storage unit that storestherein a plurality of criteria for identifying each of the image areasas one of processing areas that are subjected to different imageprocessing depending on an image segmentation mode for segmenting theimage data into the processing areas, the image processing methodcomprising: first receiving including receiving image data; extractingthe pieces of the image data corresponding to the image areas from theimage data received at the first receiving; storing the pieces of theimage data corresponding to the image areas extracted at the extractingin the first storage unit; second receiving including receiving aselection of the image segmentation mode from a user; identifying eachof the image areas as one of the processing areas based on the selectionof the image segmentation mode received at the second receiving; andperforming image processing associated with each of the processing areason the processing areas identified at the identifying.
 7. A computerprogram product comprising a computer usable medium having computerreadable program codes embodied in the medium that, when executed,causes a computer to execute the image processing method according toclaim 6.